Cold-cathode field emission devices (FEDs) are known in the art. These FEDs employ an electric field in concert with a geometric discontinuity of small radius of curvature to reduce the potential barrier and provide for increased electron tunneling from the surface of the emitter electrode. In many practical devices, the electric field is realized by supplying a voltage between the electron emitters and a gate extraction electrode. These prior art FEDs may be formed by a variety of methods, all of which yield structures with the primary purpose of emitting electrons from an emitter electrode.
In some prior art embodiments, the emitted electrons are collected by an anode that resides on a supporting structure. The anode supporting structure is generally made of insulating material and resides on the structure in which emitter electrodes and gate extraction electrodes have been formed. In other prior art embodiments, an anode may be disposed substantially co-planar with an electron emitting tip.
Although these prior art FEDs are functional, they suffer from a number of shortcomings. First, anode placement in those embodiments employing non-coplanar anodes is difficult to realize; non-coplanar FEDs require complex fabrication methods. In addition, for structures employing co-planar anode electrodes, electron emission is effected from individual sharp tips that do not maximally benefit from electric field enhancing effects. Accordingly, a need arises for an improved FED that does not suffer from these deficiencies.